Means for mounting the armature of a magnetic phonograph record reproducer and recording head



l Apu-1l 5, 1949. R. w. NlcHoLLs 2,466,469

MEANS FOR MOUNTING THE ARMATURE OF A MAGNETIC PHONOGRAPH RECORDREPRODUCER AND RECORDING HEAD Filed oct. 2e, 1945 INVENTOR.

A'ITD R N EYE Patented Apr. 5, 1949 MEAN S. FORA MQUN TIN G'THEARMATUREIOF A" NIAGNETICPHONOGRAPH" RECRD" RE- PRODUCER AND'RECORDING HEAD RalplifW-lliam Nicholls, Miami Shores, Fla.

ApplicationzOctober 26, 1945, Serial No. 6243843 37 Claims.. 1

The invention relates to a device forrecording and reproducing acousticvibrations.

The primary object of theinvention 'is' the provision ofa device-of thischaracter, wherein'the mountingl of an armature in a magnetic phonographrecord reproduceror the recording head is had' without' the usualbearings, retaining springs'or rubber damping mediums,- the device beingof novel construction and is unique` in the arrangement of its parts,for the successfuloperation thereof*I With this thought inmindthisinvention contemplates a pickup needle carried by an armature', having.a` horizontally disposed` shaft: integral therewith with an extendingend of the shaft journaled in a bearing on a base plate end with thearmature positioned between the pole pieces-of a permanent magnet of thehorseshoe type, and with coils around upwardly andodownwardlyextendingarms of thel armature and positionedin gaps in said pole pieces.

Theincorporation-of the shaft in the vibrating system of phonographvreproducers and recording cutter heads eliminates the use of rubberbearings and damping means, thus enabling the pick-up to be adj-usted toa very low` mechanical impedance, therefore, a very light pressure isrequired on the record grooves for it to track and operate successfully.This results in long usage from lacquer or commercial recordings due tothe extremely low mechanical impedance and the slight pressure on therecord.

Another object of the invention, therefore, is the provision of a deviceof this character, wherein it is simplified for manufacturingassembling, eliminates rubber bearings, springs and reduces allfriction, at the same time being rigid, but allows the armature fastenedin place to twist on an axis, the twist being slight, and the polepieces, magnet and clamp are assembled on a base plate or in a diecasting or plastic or punch pressed phonograph arm, so that very slightpressure is necessary on records which increases the number of playingsbefore surface of each is cut up by the needle, thereby increasing thelength of usefulness.

A further object of the invention is the provision of a device of thischaracter, which is simple in construction, thoroughly reliable andeicient in operation, strong, durable, neat in appearance, light inweight, and inexpensive t manufacture and install.

With these and other objects in view, the invention consists in thefeatures of construction, combination and arrangement of parts as will 2hereinafter be more Afully described, illustrated'in the accompanyingdrawing, whichishows the preferred embodiment of the invention, and ispointed out in the claims hereunto appended;

In the accompanying drawing- Fig-ure 1 is a top plan view of the deviceconstructed f in accordance with the invention;

Figure 2'y is a sectional'view taken on the-line 2-2 of Figure 1 lookingin the` direction ofthe arrows;

Figure' 3- is an elevationy of thev devicelooking towardthe needleholding endf ofI thearmature of*I the device;

Figure 4 is a detail plan view of one part of the-device removed; i

Figure 5isa sectional view taken onthe line 51-5`of Figure 4 lookinginthe direction-offl the arrows;-

Figure 6" is a crossl section throughthe device, being taken on line 6-6of'Fgure 1.

'Similar referenceV characters indicate corresponding partsthroughout'the' severaliviews in the drawing. i

Referring to the drawing in detail, theA device constituting the presentinvention, comprises an armature I 0, made as a whole with avshaft IIwhich will allow it to track in an oscillating motion. This shaft II atits inner end is removably held in a bearing I2 lby a releasable clip I3thereon, and such bearing is supported by a base plate I4, the clipbeing connected by a fastener I5.

The plate I4 supports and has insulated therefrom a U-shaped magnet I6,and disposed between the pole pieces at the ends of the two arms A-Athereof, and under the balanced inluence of the magnetic fields producedby the permanent magnet is the armature III. The pole pieces which areof ferromagnetic material, for instance, soft iron, are integral and inintimate contact with the permanent magnet I6.

Encircling the armature I 0 above and below the shaft I I are the twocoils I1 and I8, of identical construction, which coils can be connectedin series or in parallel at will and through which flows the impressedamplified current during recording and the induced current duringreproduction. The formation of the shaft Il, as indicated at I9 enablesthe tracking thereof in an oscillating motion, as before stated, as itpermits of a slight twist to such shaft, at this point I9, which shouldbe obvious.

The armature I0 is a part of the shaft II and has formed in its lowerend a clearance for a recording needle 20, adapted to be detachably heldin place by a. set screw 2l threaded into a lateral boss 22 projectedbeyond the overlying relation of the coils I1 and I8, respectively. Thebase plate I4 is also provided with a recess 23 for the passage of theneedle 20 through the same. The formation I9 of a thinned radial webconstruction, the webs being denoted at 24, respectively. A

The device constructed in accordance with the invention is devoid ofpivot bearings, springs or damping mediums, as will be apparent fromFigures 1, 2 and 3 of the drawing. It is, of course, understood that inlieu of the needle 20 a permanent sapphire point may be substituted inits place.

What is claimed is:

l. Means for mounting the needle carrying armature of a magneticphonograph reproducer or recorder comprising a bearing post xed rigidlywithin the reproducer or recorder, a hollow shaft having the armaturefixed rigidly to one end thereof and having the other end fixed rigidlyto the bearing post, the shaft being provided between the bearing postand armature with longitudinal slots presenting a pair of vertical ribsand a pair of horizontal ribs adapted to hold the shaft and its armatureagainst vertical and lateral movement but adapting the shaft to twistabout its longitudinal axis as the armature is electrically ormechanically oscillated.

2. In an armature for an electro-magnetic pickup device, a verticallydisposed armature head having a needle socket in the lower end andhaving a horizontally dispo-sed tubular shaft extended from a point inthe armature head midway of the height thereof andperpendicularlyfdisposed in relation to said head, said shaft havinglongitudinally disposed Islots therein with the slots centered indiagonally positioned planes at 45 degrees to the vertical andhorizontal planes through the shaft providing comparatively thin alignedvertical and horizontal webs connecting the ends of the shaft wherebywith the shaft supported by the end opposite to that on which thearmature head is positioned the head is suspended with the webspreventing vertical and horizontal move- 45 umher 4 ment and providingoscillating or twisting vibrations therein.

3. In an armature for an electro-magnet pickup device having a U-shapedmagnet with the armature suspended between the poles thereof, thecombination which comprises, a vertically disposed armature head havinga needle holding socket in the lower end and having a horizontallydisposed tubular shaft extended from a point in the armature head midwayof the height thereof and perpendicularly disposed in relation to saidhead, said shaft having longitudinally disposed slots therein with theslots centered on diagonally positioned planes at 45 degrees to axiallyextended vertical and horizontal planes of the shaft providingcomparatively thin aligned vertical and horizontal webs connecting theends of the shaft whereby with the shaft supported by the end oppositeto that on which the armature is positioned the head is suspended withthe webs preventing vertical and horizontal movement and providingoscillating or twisting vibration in the shaft, and a bearing post inwhich the end of the shaft opposite to that on which the armature headis positioned, for supporting the armature with the said shaft thereofpositioned midway between the arms of the U-shaped magnet and in a planeextended through said arms and midway of the width thereof.

RALPH WILLIAM VNICHOLIS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date Crouse Nov. 24, 1931 Guedon Mar. 19,1935 Harrison s Jan. 7, 1936 Kendall Sept. 14, 1937 FOREIGN PATENTSCountry Date Great `Britain Apr. 24, 1940 Number

